My research objective is to determine the role of lymphocyte DNA synthesis in propagating the immune response and lymphoid malignancies. Human lymphocytes stimulated in vitro by phytohemagglutinin synthesize extra copies of a limited portion of their genome and excrete this DNA into the culture medium. As measured by Cot analysis, this excreted DNA is composed of unique sequence elements representing a complexity of 10 percent of the genome. A functional role for the excreted DNA has not been determined, but it might be important in intercellular communication during the immune response. In order to determine if excreted DNA can be associated with some function, experiments utilizing hybridization to various classes of DNA, experiments characterizing the physical structure of the intracellular precursor to excreted DNA, and experiments dealing with agents that induce specific release of the DNA will be performed. BIBLIOGRAPHIC REFERENCES: Rogers, John C. Characterization of DNA Excreted from Phytohemagglutinin-Stimulated Lymphocytes. J. Exp. Med., 143: 1249-1264, 1976. Rogers, John C. Identification of an intracellular precursor to DNA excreted by human lymphocytes. Proc. Nat. Acad. Sci. USA, 73:3211-3215, 1976.